See also:

• GEM (Lat. gemma, a bud,—from the root gen, meaning " to produce,"—or precious stone; in the latter sense the Greek term is > d>os)
• GEM, ARTIFICIAL

GEM (See also:

• LAT

Lat. gemma, a bud,—from the See also:

• ROOT (late O.E. rot, adopted from Scand., cf. Norw. and Swed. rot, Dan. rod; the true O.E. word was wyrt, plant, represented in Ger. Wurz or Wurzel; the ultimate root is the same in both words, and is seen in Lat. radix)
• ROOT, ELIHU (1845– )

root gen, meaning " to produce,"—or See also:

• PRECIOUS (O. Fr. precios, mod. precieux, Lat. pretiosus, of high value or price, pretium)

precious See also:

• STONE
• STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
• STONE, CHARLES POMEROY (1824-1887)
• STONE, EDWARD JAMES (1831-1897)
• STONE, FRANK (1800-1859)
• STONE, GEORGE (1708—1764)
• STONE, LUCY [BLACKWELL] (1818-1893)
• STONE, MARCUS (184o— )
• STONE, NICHOLAS (1586-1647)

stone; in the latter sense the See also:

• GREEK
• GREEK, ETRUSCAN AND

Greek See also:

• TERM

term is > d>os)  , a word applied in a wide sense to certain minerals which, by See also:

• REASON (Lat. ratio, through French raison)

reason of their brilliancy, hardness and rarity, are valued for See also:

• PERSONAL

personal decoration; it is extended to include See also:

• PEARL
• PEARL, THE

pearl . In a restricted sense the See also:

• TERM

term is applied only to See also:

• PRECIOUS (O. Fr. precios, mod. precieux, Lat. pretiosus, of high value or price, pretium)

precious stones after they have been cut and polished as jewels, whilst in their raw See also:

• STATE
• STATE, GREAT OFFICERS OF

state the minerals are conveniently called " See also:

• GEM (Lat. gemma, a bud,—from the root gen, meaning " to produce,"—or precious stone; in the latter sense the Greek term is > d>os)
• GEM, ARTIFICIAL

gem-stones." Some-times, again, the term " gem " is used in a yet narrower sense, being restricted to engraved stones, like See also:

• SEALS

seals and cameos . The subject is treated here in two sections: (I) See also:

• MINERALOGY

Mineralogy and See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general properties; (2) Gems in See also:

• ART

Art, i.e. engraved gems, such as seals and cameos . The artificial products which simulate natural gem-stones in properties and chemical See also:

• COMPOSITION
• COMPOSITION (Lat. compositio, from componere, to put together)

composition are treated in the See also:

• SEPARATE

separate See also:

• ARTICLE (from Lat. articulus, a joint)

article GEM, ARTIFICIAL . I . MINERALOGY AND GENERAL PROPERTIES The gem-stones See also:

• FORM (Lat. forma)

form a small conventional See also:

• GROUP

group of minerals, including principally the See also:

• DIAMOND

diamond, See also:

• RUBY (Lat. rubeus, red)

ruby, See also:

• SAPPHIRE

sapphire, See also:

• EMERALD

emerald and See also:

• OPAL

opal . Other stones of less value—such as See also:

• TOPAZ

topaz, See also:

• SPINEL

spinel, See also:

• CHRYSOBERYL

chrysoberyl, See also:

• CHRYSOLITE

chrysolite, See also:

• ZIRCON

zircon and See also:

• TOURMALINE

tourmaline—are sometimes called " See also:

• FANCY (a shortened form, dating from the 15th century, of " fantasy," which is derived through the O. Fr. fantasie, modern fantaisie. from the Latinized form of the Gr. cbavraoia, Oavrai'ecv, Oat Pais, to show)

fancy stones." Many minerals still less prized, yet often used as ornamental stones,—like See also:

• MOONSTONE

moonstone, See also:

• ROCK
• ROCK (O.Fr. rake, Sp. rota, Ital. rocca; possibly from a Lat. form rupica, from rupes, rock)
• ROCK, DANIEL (1799–187t)

rock-crystal and See also:

• AGATE

agate,—occasionally pass under the name of " semi-precious stones," but this is rather a vague term and may include the stones of the preceding group . The See also:

• CLASSIFICATION (Lat. classis, a class, probably from the root cal-, cla-, as in Gr. icaMce, clamor)

classification of gem-stones is, indeed, to some extent a See also:

• MATTER

matter of See also:

• FASHION (adapted from Fr. facon, agon, Lat. factio, making, facere, to do or make)

fashion . Descriptions of the several gem-stones will be found under their respective headings, and the See also:

• PRESENT

present article gives only a brief See also:

• REVIEW (Fr. revue, from revoir, to see again, Lat. re and videre)

review of the general characters of the group . A high degree of hardness is an essential See also:

• PROPERTY

property of a gem-See also:

• STONE
• STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
• STONE, CHARLES POMEROY (1824-1887)
• STONE, EDWARD JAMES (1831-1897)
• STONE, FRANK (1800-1859)
• STONE, GEORGE (1708—1764)
• STONE, LUCY [BLACKWELL] (1818-1893)
• STONE, MARCUS (184o— )
• STONE, NICHOLAS (1586-1647)

stone, for however beautiful and brilliant a See also:

• MINERAL

mineral may be it is Hardness. useless to the jeweller if it lack sufficient hardness to withstand the See also:

• ABRASION (from Lat. ab, off, and radere, to scrape)

abrasion to which articles of personal decoration are necessarily subjected . Even if not definitely scratched, the polished stone becomes dull by See also:

• WEAR

wear . Imitations in See also:

• PASTE (O. Fr. paste, modern pate, Late Lat. pasta, whence also in Span., Port. and Ital., from Gr. 1r&vrrl or 1raara, barley porridge, or salted pottage, ir&ao'ety, to sprinkle with salt)

paste may be extremely brilliant, but being comparatively soft they soon lose lustre when rubbed .

In the article MINERALOGY it is explained that the varying degrees of hardness are registered on a definite See also:

• SCALE
• SCALE (1) A

scale . The exceptional hardness of the diamond gives it a supreme position in this scale, and to it the arbitrary value of 10 has been assigned . The See also:

• CORUNDUM

corundum gem-stones (ruby and sapphire), though greatly inferior in hardness to the diamond, come next, with the value of 9; and it is notable that the sapphire is usually rather harder than ruby . Then follows the topaz, which, with spinel and chrysoberyl, has a hardness of 8; whilst See also:

• QUARTZ

quartz falls a degree See also:

• LOWER

lower . Most gem-stones are harder than quartz, though precious opal, See also:

• TURQUOISE

turquoise, moonstone and See also:

• SPHENE

sphene are inferior to it in hardness . Those stones which are softer than quartz have been called by jewellers demi-dures . To test the hardness of a cut stone, one of its See also:

• SHARP, GRANVILLE (1735-1813)
• SHARP, JAMES (1618-1679)
• SHARP, JOHN (1645-1714)
• SHARP, RICHARD (1759-1835)
• SHARP, WILLIAM (1749-1824)
• SHARP, WILLIAM (1856-1905)

sharp edges may be See also:

• DRAWN

drawn, with See also:

• FIRM

firm pressure, across the smooth See also:

• SURFACE

surface of a piece of quartz; if it leave a scratch its hardness must be above 7 . The stone is then applied in like manner to a fragment of topaz, preferably a cleavage-piece, and if it fail to leave a distinct scratch its hardness is between 7 and 8, whereas if the topaz be scratched it is above 8 . An See also:

• EXPERT (Lat. expertus, from experiri, to try)

expert may obtain a See also:

• FAIR

fair See also:

• IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea of hardness by gently passing the stone over a See also:

• FINE

fine See also:

• STEEL, FLORA ANNIE (1847– )

steel See also:

• FILE

file, and observing the feel of the stone and the grating See also:

• SOUND
• SOUND, THE (Danish Oresund)

sound which it emits . If a stone be scratched by a steel See also:

• KNIFE (0. E. cuff, a word appearing in different forms in many Teutonic languages, cf. Du. knijf, Ger. Kneif, a shoe-maker's knife, Swed. knif; the ultimate origin is unknown; Skeat finds the origin in the root of " nip," formerly " knip "; Fr. canif is a

knife its hardness is below 6 . The degree of hardness of a precious stone is soon ascertained by the See also:

• LAPIDARY

lapidary when cutting it . Gem-stones differ markedly among themselves in See also:

• DENSITY (Lat. densus, thick)

density or specific See also:

• WEIGHT

weight; and although this is a See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character which does not directly affect their value for ornamental purposes, it furnishes by its constancy an important means of distinguishing one stonefrom another .

Moreover, it is a character very easily determined and can be applied to cut stones without injury . The relative weightiness of a stone is called its specific gravity, and is often abbreviated as S.G . The number given in speclfk gravity. the description of a mineral as S.G. shows how many times the stone is heavier than an equal bulk of the See also:

• STANDARD
• STANDARD, BATTLE OF THE

standard with which it is compared, the standard being distilled See also:

• WATER

water at 4° C . If, for example, the S.G. of diamond is said to be 3.5 it means that a diamond weighs 3i times as much as a See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass of water of the same bulk . The various methods of determining specific gravity are described under DENSITY . The readiest method of testing precious stones, especially when cut, is to use dense liquids . Suppose it be required to determine whether a yellow stone be true topaz or false topaz (quartz), it is merely necessary to drop the stone into a liquid made up to the specific gravity of about 3; and since topaz has S.G. of 3.5 it sinks in this See also:

• MEDIUM

medium, but as quartz has S.G. of only 2.65 it floats . The densest gem-stone is zircon, which may have S.G. as high as 4.7, whilst the lowest is opal with S.G . 2.2 . See also:

• AMBER

Amber, it is true, is lighter still, being scarcely denser than water, but this substance can hardly be called a gem . Although the See also:

• GREAT

great See also:

• MAJORITY (Fr. majorite; Med. Lat. majoritas; Lat. major, greater)

majority of precious stones occur crystallized, the characteristic form is destroyed in cutting . The crystal-forms of the several stones are noticed under their respective headings, and the subject is discussed Crystal~me fully under See also:

• CRYSTALLOGRAPHY
• CRYSTALLOGRAPHY (from the Gr. Kpbo TaXXO , ice, and -ypachew, to write)

CRYSTALLOGRAPHY .

A few substances cleavage. used as ornamental stones—like opal, turquoise, See also:

• OBSIDIAN

obsidian and amber—are amorphous or without crystalline form; whilst others, like the various stones of the See also:

• CHALCEDONY, or CALCEDONY (sometimes called by old writers cassidoine)

chalcedony-group, display no obvious crystal-characters, but are seen under the See also:

• MICROSCOPE (Gr. µucp6s, small, asenreiv, to %view)

microscope to possess a crystalline structure . Gem-stones are frequently found in gravels or other detrital deposits, where they occur as rolled crystals or fragments of crystals, and in many cases have been reduced to the form of pebbles . By the disintegration of the rock which formed the See also:

• ORIGINAL

original See also:

• MATRIX

matrix, its constituent minerals were set See also:

• FREE

free, and whilst many of them were worn away by See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long-continued See also:

• ATTRITION (Lat. attritio, formed from atterere, to rub away)

attrition, the gem-stones survived by virtue of their See also:

• SUPERIOR

superior hardness . Many crystallized gem-stones exhibit cleavage, or a tendency to split in definite directions . The lapidary recognizes a " See also:

• GRAIN (derived through the French from Lat. granum, seed, from an Aryan root meaning " to wear down," which also appears in the common Teutonic word " corn ")

grain " in the stone . When the cleavage is perfect, as in topaz, it may render the working of the stone difficult, and produce incipient cracks in the cut gem . Flaws due to the cleavage planes are called " feathers." The octahedral cleavage of the diamond is taken See also:

• ADVANTAGE

advantage of in dressing the stone before cutting it . The cutting of gem-stones is explained under LAPIDARY . The beauty and consequent value of gems depend mainly on their See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour . Some stones, it is true, are valued for entire See also:

• ABSENCE (Lat. absentia)

absence of colour, as diamonds of pure " water." Colour . Certain kinds of sapphire and topaz, too, are " water clear," as also is pure rock-crystal; but in most stones colour is a See also:

• PRIME, PRIMER AND PRIMING

prime See also:

• ELEMENT (Lat. elementum)

element of attraction . The colour, however, is not generally an essential property of the mineral, but is due to the presence of See also:

• FOREIGN

foreign pigmentary matter, often in very small proportion and in some cases eluding determination .

Thus, corundum when pure is colourless, but the presence of traces of certain mineral sub-stances imparts to it not only the red of ruby and the See also:

• BLUE (common in different forms to most European languages)

blue of sapphire, but almost every other colour . The tinctorial matter may be distributed either uniformly throughout the stone or in See also:

• REGULAR

regular zones, or in quite irregular patches . A tourmaline, for instance, may be red at one end of a prismatic crystal and See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green at the other extremity, or the colour may be so disposed that in transverse See also:

• SECTION
• SECTION (Lat. sectio, cutting, secare, to cut)

section the centre will be red and the See also:

• OUTER

outer See also:

• ZONE (Gr. 'WV77, a girdle, from 'wvvLvay to gird)

zone green . A See also:

• BERYL

beryl may be yellow and green in the same crystal . Sapphire, again, is often parti-coloured, one portion of the stone being blue and other portions See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white or yellow; and the skilful lapidary, in cutting the stone, will take advantage of the blue portion . The character of the pigment is in many cases not definitely known . It by no means follows that the material capable of imparting a certain tint to See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass is identical with that which naturally See also:

• COLOURS, MILITARY

colours a stone of the same tint; thus a glass of sapphire-blue may be obtained by the use of See also:

• COBALT (symbol Co, atomic weight 59)

cobalt, yet cobalt has not been detected in the sapphire . Probably the most See also:

• COMMON

common absorption . It is sometimes useful to examine the behaviour of a stone under the See also:

• ACTION

action of the See also:

• RONTGEN, DAVID
• RONTGEN, WILHELM KONRAD (1845– )

Rontgen rays . A very useful means of discriminating between certain stones is found in their dichroism, or, to use a more general term, pleochroism . Neither amorphous minerals, like opal, nor minerals crystallizing in the cubic See also:

• SYSTEM

system, like Wlsmkh .re' i spinel and See also:

• GARNET
• GARNET, or GARNETT, HENRY (1555—1606)

garnet, possess this property; but coloured minerals which are doubly refracting may show different colours, when properly examined, in different directions . Occasionally this is so marked as to be detected by the naked See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye, as in See also:

• IOLITE

iolite or dichroite, but usually the stone needs to be examined with such an See also:

• INSTRUMENT (Lat. instrumentum, from insincere, to build up, furnish, arrange, prepare)

instrument as See also:

• HAIDINGER, WILHELM KARL, RITTER VON (1795-1871)

Haidinger's dichroscope (see CRYSTALLOGRAPHY) .

It must be remembered that in the direction of an optic See also:

• AXIS (Lat. for " axle ")

axis the two images will be of the same colour in all positions of the instrument, and it is therefore necessary before reachirg a definite conclusion to turn the stone about and examine it in various directions . The use of the dichroscope is so See also:

• SIMPLE

simple that it can be applied by any one to the examination of a cut stone, but there are other means of determining the nature of a stone by its See also:

• OPTICAL

optical properties available to the mineralogist and more suitably discussed under CRYSTALLOGRAPHY . In chemical composition the gem-stones present great variety . Diamond is composed of only a single element; ruby, sapphire and the quartz-group are oxides; spinel and chryso- beryl may be regarded as aluminates; turquoise and chemical See also:

• BERYLLONITE

beryllonite are See also:

• PHOSPHATES

phosphates; and a great number of aPOs ornamental stones are silicates of greater or less complexity, such as emerald, topaz, chrysolite, garnet, zircon, tourmaline, See also:

• KUNZITE

kunzite, sphene and See also:

• BENITOITE

benitoite . In the examination of a cut stone chemical tests are not available, since they usually involve the partial destruction of the mineral . The artificial See also:

• PRODUCTION (Lat. productionem, from producere, to pro-duce)

production of certain gems by chemical processes which yield products identical in composition and See also:

• PHYSICAL

physical properties with the natural stones, is described in the article GEM, ARTIFICIAL . Doublets and triplets are composite stone, sometimes prepared for fraudulent purposes . In a doublet a slab of real gem-stone covers the See also:

• FACE (from Lat. fades, derived either from facere, to make, or from a root fa-, meaning " appear "; cf. Gr. cbatvstv)

face of a paste, whilst in a triplet the paste is both faced and backed by a slice of genuine stone . By the action of a suitable solvent, such as See also:

• CHLOROFORM (trichlor-methane), CHC13

chloroform or in some cases even hot water, the See also:

• CEMENT (from Lat. caementum, rough pieces of stone, a shortened form of caedimentum, from caedere, to cut)

cement uniting the pieces gives way and' the See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound character of the structure is detected . Before the chemical composition of gem-stones was understood, their classification remained vague and unscientific . As the ancients depended almost entirely on the eye, the colour of the stone naturally became the See also:

• CHIEF (from Fr. chef, head, Lat. caput)

chief See also:

• FACTOR (from Lat. facere, to make or do)

factor in classification . A variety of stones agreeing roughly in colour would be grouped together under a common name, widely as they might differ in other respects .

Thus the emerald, the See also:

• PERIDOT

peridot, green fluorspar, See also:

• MALACHITE

malachite, and certain kinds of quartz and See also:

• JADE
• JADE, or JAHDE

jade seem to have been See also:

• UNITED

united under the general name of Qµapaybos; whilst the ruby, red spinel and garnet were probably grouped together as carbuntulus . In this way minerals radically different were associated on the ground of what is generally a superficial and accidental character, and rarely of any classificatory value . On the other See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, a grouping based only on colour led to several names being in some cases applied to the same mineral See also:

• SPECIES

species . Thus the ruby and sapphire are essentially identical in chemical composition and in all physical characters, See also:

• SAVE, or SAVA (Ger. Sau; Hungarian Szdva; Lat. Savus)

save colour . Descriptions of precious stones by See also:

• ANCIENT
• ANCIENT (also spelt ANTIENT; derived, through the Fr. ancien, old, from the late Lat. antianum, from ante, before)

ancient writers generally are too vague for exact diagnosis . The See also:

• PRINCIPAL

principal classical authorities are See also:

• THEOPHRASTUS

Theophrastus and the See also:

• ELDER (0. Eng. ellarn; Ger. Holunder; Fr. sureau)
• ELDER (Gr. 1rpev(3iTepos)

elder See also:

• PLINY, THE ELDER
• PLINY, THE YOUNGER

Pliny . Stones were superstiformerly held in esteem not only for their beauty and Woos, rarity but for the medicinal and magical See also:

• POWERS, HIRAM (1805-1873)

powers with which they were reputed to be endowed . Up to comparatively See also:

• RECENT

recent years the toadstone, for example, was worn not for beauty but for See also:

• SAKE

sake of occult virtue; and even at the present See also:

• DAY (O. Eng. dreg, Ger. Tag; according to the New English Dictionary, " in no way related to the Lat. dies")
• DAY, JOHN (1574-1640?)
• DAY, THOMAS (1748-1789)

day certain stones, like jade, are valued for a similar reason . Prof . -W . Ridgeway has suggested that See also:

• JEWELRY (O. Fr. jouel, Fr. joyau, perhaps from joie, joy; Lat. gaudium; retranslated into Low Lat. jocale, a toy, from jocus, by misapprehension of the origin of the word)

jewelry took its origin not, as cften supposed, in an innate love of personal decoration, but rather in the belief that the See also:

• OBJECTS

objects used possessed magical virtue . Small stones See also:

• PECULIAR

peculiar in colour or shape, especially those with natural perforations, are usually valued by uncivilized peoples mineral See also:

• PIGMENTS (Lat. pigmentum, from pingere, to paint)

pigments are compounds of See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron, See also:

• MANGANESE (symbol Mn; atomic weight, 54.93 (0=16)], a metallic chemical element. Its dioxide (pyrolusite)

manganese, See also:

• COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper and See also:

• CHROMIUM (symbol Cr. atomic weight 52.1)

chromium .

If the colour of the stone be discharged by See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat, an organic pigment is presumably present . Some ornamental stones See also:

• CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change their colour, or even lose it, on exposure to sunlight and See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air: such is the See also:

• CASE
• CASE, JOHN (d. 1600)

case with See also:

• ROSE
• ROSE (Rosa)
• ROSE, GEORGE (1744-1818)
• ROSE, HUGH JAMES (1795—1838)
• ROSE, WILLIAM STEWART (1775-1843)

rose-quartz, See also:

• CHRYSOPRASE (Gr. Xpvvor, gold, and apaorov, leek)

chrysoprase and certain kinds of topaz and turquoise . Exposure to heat alters the colour of some stones so readily that the change is taken advantage of commercially; thus, See also:

• SHERRY

sherry-yellow topaz may be rendered See also:

• PINK

pink, smoky and amethystine quartz may become yellow, and coloured zircons may be decolorized, so as to resemble diamonds . The colours of some gem-stones are greatly affected by radio-activity, and Prof . F . Bordas has found this to be particularly the case with sapphire . From his experiments he believes that yellow corundum, or See also:

• ORIENTAL

oriental topaz, may have been formed from blue corundum under the See also:

• INFLUENCE (Late Lat. influentia, from influere, to flow in)

influence of radioactive substances present in the See also:

• SOIL

soil in which the sapphire was embedded . Different shades of colour may be presented by different stones of the same species; and it was formerly the See also:

• CUSTOM (from O. Fr. costume, costume or coustume; Low Lat. costuma, a shortened form of consuetudo)

custom of lapidaries to regard the darker stones as masculine and the paler as feminine, a full blue sapphire, for instance, being called a " male sapphire " and a delicate blue stone a " See also:

• FEMALE

female sapphire." It is notable that some stones appear to change colour by See also:

• CANDLE (Lat. candela, from candere, to glow)

candle-See also:

• LIGHT

light and by most other artificial means of See also:

• ILLUMINATION

illumination; some amethysts thus become inky, and certain sapphires acquire a murky tint, whilst others become amethystine . For an example of a remark-able change of this character, see See also:

• ALEXANDRITE

ALEXANDRITE .